An attempt is made to identify the significance of seasonal variations on the structural performance of flexible pavements, based on the interpretation of surface deflections measured at different times of the year using the Falling Weight Deflectometer (FWD). Data from field surveys carried out on UK sites, near Wakefield and Chester, are analysed and discussed. Reference is also made to other similar testing programmes reported in the literature. The results show the well-known dependency of the elastic modulus of bituminous materials with temperature. With respect to the granular layers and subgrades, the back-calculated moduli exhibit a variation with season, being consistently higher in summer and autumn than in winter and spring. However, for the environmental conditions considered, the magnitude of these seasonal changes is usually small. (A)
Abstract